US20010044277A1 - Method and device for digital wireless transmission of audio signals - Google Patents

Method and device for digital wireless transmission of audio signals Download PDF

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Publication number
US20010044277A1
US20010044277A1 US09/726,623 US72662300A US2001044277A1 US 20010044277 A1 US20010044277 A1 US 20010044277A1 US 72662300 A US72662300 A US 72662300A US 2001044277 A1 US2001044277 A1 US 2001044277A1
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US
United States
Prior art keywords
clock
player
receiver
sender
digital
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US09/726,623
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English (en)
Inventor
Andreas Kremsl
Peter Schlager
Werner Lang
Kurt Nell
Ernst Stöttinger
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AKG Acoustics GmbH
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AKG Acoustics GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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Assigned to AKG ACOUSTICS GMBH reassignment AKG ACOUSTICS GMBH ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KREMSL, ANDREAS, LANG, WERNER, NELL, KURT, SCHLAGER, PETER, STOTTINGER, ERNST
Publication of US20010044277A1 publication Critical patent/US20010044277A1/en
Abandoned legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/86—Arrangements characterised by the broadcast information itself
    • H04H20/88—Stereophonic broadcast systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00—Arrangements for synchronising receiver with transmitter
    • H04L7/0091—Transmitter details
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04S—STEREOPHONIC SYSTEMS 
    • H04S3/00—Systems employing more than two channels, e.g. quadraphonic
    • H04S3/002—Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution
    • H04S3/004—For headphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00—Arrangements for synchronising receiver with transmitter
    • H04L7/0016—Arrangements for synchronising receiver with transmitter correction of synchronization errors
    • H04L7/002—Arrangements for synchronising receiver with transmitter correction of synchronization errors correction by interpolation
    • H04L7/0029—Arrangements for synchronising receiver with transmitter correction of synchronization errors correction by interpolation interpolation of received data signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L7/00—Arrangements for synchronising receiver with transmitter
    • H04L7/02—Speed or phase control by the received code signals, the signals containing no special synchronisation information
    • H04L7/033—Speed or phase control by the received code signals, the signals containing no special synchronisation information using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop

Definitions

  • the invention relates to a method and a device for digital wireless transmission of multi-channel audio signals.
  • Such methods and devices for example, are used for wireless transmission of audio signals from players to headphones.
  • This steric hearing effect experienced by the human is produced, on the one hand, in that the sound of a point-shaped sound source reaches the two ears of the human with a slight temporal difference (except where the sound source is positioned in the symmetry plane between the ears) and, on the other hand, due to the fact that the hearing of the human, viewed as a sum total including reflection and absorptions at the shoulders etc., has an extremely complex directional characteristic which changes greatly depending on the incident angle of the incident signal until it finally reaches the eardrum.
  • the unconscious knowledge of this characteristic which differs from human to human, makes it possible for the human to locate a sound source within a space.
  • cordless headphones has been known for a long time.
  • the headphones are operated by means of batteries or accumulators and the signal transmission is realized by radio or infrared signals.
  • the receiver circuitry also comprises a clock generator which, after completed synchronization, controls the further processing of the signals up to the point of detecting a successive control bit sequence in the incoming cycle and, when detecting the successive control bit sequence, then controls the synchronization and, if needed, repeats synchronization.
  • the information transmitted by the sender is that supplied by the electronic circuitry of the player; in these playing devices clock generators are provided which were able to fulfilled the requirements of the past wherein, of course, the congruence of the clock frequency between the devices was of no consequence because these devices work independent of one another and are not connected to one another. To this end, it is only necessary to provide clock stability which is sufficient to allow internal information-processing within the device and to prevent the generation of audible effects.
  • the tolerance range for the bit rate of audio signals is ⁇ 1,000 ppm.
  • the jitter-free clock recovery for such great differences of the bit rate is possible only with a very wide broadband phase locked loop and very low noise level. If it is desired to suppress the jitter despite a high noise level, as is often the case for wireless transmission, the phase locked loop must be of a very narrow narrowband design, and this has the consequence that it locks only very slowly so that the audio transmission takes an unacceptable amount of time.
  • phase locked loop which is referred to as clock recovery
  • the spacing of the pulse flanks of the clock signals (clock pulses) self-generated within the receiver are compared with the pulse flanks of the incoming data flow and, based on the determined temporal differences of the compared flanks, an error signal is derived with which the frequency and phase of the self-generated clock frequency is controlled and adjusted.
  • the clock recovery is perfect, and this is referred to as the locked state.
  • this is achieved in that the signal picked up by the player and optionally converted into a stereo signal is scanned by means of a scanning rate converter provided in the sensor with clock pulses provided by a quartz-controlled clock generator and that the clock generator of the sender is at least substantially precisely adjusted to the center frequency of a preferably voltage-controlled quartz oscillator of the clock recovery provided in the receiver.
  • the scanning rate converter is replaced by a combination of a digital-to-analog converter connected at the analog side with an analog-to-digital converter.
  • the signal which is reduced at the device side to two channels, is adjusted, independent of the quartz element of the player, by means of the scanning rate converter to a cycle rate which is practically constant from device to device as well as within the operating conditions and the service life of the device and which thus interacts as best as possible with the clock recovery control circuit provided at the receiver.
  • the noise bandwidth of the clock recovery is also correspondingly small. Accordingly, it is very insensitive with respect to noise and disturbances so that the loss of the lock, i.e., losing the signal, can be reliably prevented in practically all cases within the receiving range of the receiver.
  • clock adjustment Since the clock adjustment is carried out in the sender, no new components are required in the receiver which is beneficial with respect to the wearing comfort in the case of headphones as well as with regard to the energy consumption in the case of battery operation. Since this clock adjustment is carried out at a location of the data flow where it is present in the two-channel form, i.e., as a stereo signal, the expenditure for the required components and thus the investment and labor costs are minimal.
  • FIG. 1 illustrates the configuration of a sender according to the prior art
  • FIG. 2 illustrates a special prior art embodiment of the sender according to patent document WO 97/25834.
  • FIG. 3 shows schematically the sender according to the present invention.
  • the sender 1 cooperating with the players according to the prior art is comprised of a Dolby decoding device 2 ; a binaural synthesizing circuit 3 , whose output is a stereo signal, which according to the prior art is changed in a modifying unit 4 in order to prevent loss of the signal of the clock recovery in the receiver as much as possible; an encoding device 5 arranged downstream which combines the two signal flows to a continuous signal flow; and a UHF component 6 in which the signal flow modulates the carrier signal generated in the UHF component and emitted via the antenna 7 . All components which are used in this embodiment according to the prior art are clocked by the clock pulses 16 of the clock generator of the player. This results in the above-mentioned disadvantages, in particular, a considerable jitter, and causes the problems to be solved by the present invention.
  • FIG. 2 shows one of the two modifying devices 4 .
  • the incoming signal is overlaid by a noise signal of a noise generator 9 at the combination location 8 so that reliably a sufficient number of flanks is formed which can be recognized and used by the clock recovery in the receiver.
  • the binary signal is converted in the filter 10 into a bipolar signal so that the switching threshold is set to zero volt and the noise becomes effective when over a longer period of time no pulse flank occurs.
  • An additional measure is the subsequent “exclusive or” which combines the data flow with an alternating bit sequence; this is also done to provide a sufficient number of flanks.
  • the digital signal modulated by noise via the sender is processed in the receiver—a digital wireless headphone—such that the overlaid noise is again removed and the alternating bit sequence is also again converted into the original sequence.
  • the spectrally widened signal is filtered out by means of a phase locked loop which corresponds to a cleanup loop. This method is referred to as clock recovery.
  • jitter In absolute values it can be stated that the effective value of an jitter should not surpass 100 picoseconds because otherwise it is already audible as a disturbance.
  • jitter When viewed as a spectral function, jitter can be viewed as sideband noise of the clock signal, and its suppression can be carried out during clock recovery by means of a narrowband filter.
  • the sender according to the invention is configured as illustrated schematically in FIG. 3 by means of a block diagram.
  • a Dolby decoding device 2 is provided and at the output a multi-channel signal is present which is converted by the binaural synthesizing circuit 3 into a stereo signal.
  • This stereo signal is supplied according to the invention to a scanning rate converter 14 (for each channel) whose clock pulses 17 at the output side are generated by the clock generator 15 provided according to the invention.
  • this clock generator 15 is precise and stable within a narrowly predefined frame so that the data flow supplied to the encoder 5 after its combination within the high frequency component 6 can modulate also the carrier signal to be modulated with high precision so that the recovery circuit at the receiver side can be designed with minimal sensitivity and thus high stability.
  • the encoding device and the modulating device are also controlled and cycled by the clock generator 15 provided at the sender.
  • the jitter is reduced to such an extent that the phase locked loop (PLL) can have such a high quality that it is able to bridge even several disturbed intervals (i.e., it thus scans and evaluates in a quasi blind way, within its on responsibility, the received signal) before it requires again a measurable flank for locking.
  • PLL phase locked loop
  • the same can be achieved by employing a digital-to-analog converter and an analog-to-digital converter whose analog sides are oriented toward one another.
  • the input digital signal is converted to an analog signal in the digital-to-analog converter and is transformed with the precisely cycled analog-to-digital converter into a jitter-free digital data stream.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Stereophonic System (AREA)
  • Synchronisation In Digital Transmission Systems (AREA)
  • Transmitters (AREA)
  • Stereo-Broadcasting Methods (AREA)
  • Headphones And Earphones (AREA)
US09/726,623 1999-12-03 2000-11-30 Method and device for digital wireless transmission of audio signals Abandoned US20010044277A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AT0204099A AT408298B (de) 1999-12-03 1999-12-03 Verfahren und vorrichtung zur digitalen funk-übertragung von audiosignalen
ATA2040/99 1999-12-03

Publications (1)

Publication Number Publication Date
US20010044277A1 true US20010044277A1 (en) 2001-11-22

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Family Applications (1)

Application Number Title Priority Date Filing Date
US09/726,623 Abandoned US20010044277A1 (en) 1999-12-03 2000-11-30 Method and device for digital wireless transmission of audio signals

Country Status (4)

Country Link
US (1) US20010044277A1 (ja)
EP (1) EP1119121A3 (ja)
JP (1) JP2001237724A (ja)
AT (1) AT408298B (ja)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060153155A1 (en) * 2004-12-22 2006-07-13 Phillip Jacobsen Multi-channel digital wireless audio system
US20080186999A1 (en) * 2006-11-20 2008-08-07 Siverge Ltd. Methods and apparatuses for circuit emulation multi-channel clock recovery
EP2506943A1 (en) * 2009-12-02 2012-10-10 Astro Gaming, Inc. Wireless game/audio system and method
US10129631B2 (en) 2015-08-26 2018-11-13 Logitech Europe, S.A. System and method for open to closed-back headset audio compensation

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101166363B1 (ko) 2006-09-04 2012-07-23 엘지전자 주식회사 무선 스피커에서의 동기 보정 장치 및 방법

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5596603A (en) * 1993-08-23 1997-01-21 Sennheiser Electronic Kg Device for wireless transmission of digital data, in particular of audio data, by infrared light in headphones
US6307868B1 (en) * 1995-08-25 2001-10-23 Terayon Communication Systems, Inc. Apparatus and method for SCDMA digital data transmission using orthogonal codes and a head end modem with no tracking loops
US6356160B1 (en) * 1999-07-02 2002-03-12 Xilinx, Inc. Phase lock loop and automatic gain control circuitry for clock recovery
US6519448B1 (en) * 1998-09-30 2003-02-11 William A. Dress Personal, self-programming, short-range transceiver system
US6563880B1 (en) * 1994-07-12 2003-05-13 Ibiquity Digital Corporation Method and system for simultaneously broadcasting and receiving digital and analog signals
US6614849B1 (en) * 1999-10-25 2003-09-02 Free Systems Pte. Ltd. Wireless infrared digital audio receiving system

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1997025834A2 (en) * 1996-01-04 1997-07-17 Virtual Listening Systems, Inc. Method and device for processing a multi-channel signal for use with a headphone
WO1999018761A2 (de) * 1997-10-06 1999-04-15 Jens Kurrat Vorrichtung zur drahtlosen übertragung digitaler daten, insbesondere audiodaten

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5596603A (en) * 1993-08-23 1997-01-21 Sennheiser Electronic Kg Device for wireless transmission of digital data, in particular of audio data, by infrared light in headphones
US6563880B1 (en) * 1994-07-12 2003-05-13 Ibiquity Digital Corporation Method and system for simultaneously broadcasting and receiving digital and analog signals
US6307868B1 (en) * 1995-08-25 2001-10-23 Terayon Communication Systems, Inc. Apparatus and method for SCDMA digital data transmission using orthogonal codes and a head end modem with no tracking loops
US6519448B1 (en) * 1998-09-30 2003-02-11 William A. Dress Personal, self-programming, short-range transceiver system
US6356160B1 (en) * 1999-07-02 2002-03-12 Xilinx, Inc. Phase lock loop and automatic gain control circuitry for clock recovery
US6614849B1 (en) * 1999-10-25 2003-09-02 Free Systems Pte. Ltd. Wireless infrared digital audio receiving system

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060153155A1 (en) * 2004-12-22 2006-07-13 Phillip Jacobsen Multi-channel digital wireless audio system
US8050203B2 (en) 2004-12-22 2011-11-01 Eleven Engineering Inc. Multi-channel digital wireless audio system
US20080186999A1 (en) * 2006-11-20 2008-08-07 Siverge Ltd. Methods and apparatuses for circuit emulation multi-channel clock recovery
US7924885B2 (en) * 2006-11-20 2011-04-12 Siverge Networks Ltd Methods and apparatuses for circuit emulation multi-channel clock recovery
EP2506943A1 (en) * 2009-12-02 2012-10-10 Astro Gaming, Inc. Wireless game/audio system and method
EP2506943A4 (en) * 2009-12-02 2014-03-26 Acquisition Corp Ag WIRELESS GAME AND AUDIO SYSTEM AND METHOD THEREFOR
US10124264B2 (en) 2009-12-02 2018-11-13 Logitech Europe, S.A. Wireless game/audio system and method
US10129631B2 (en) 2015-08-26 2018-11-13 Logitech Europe, S.A. System and method for open to closed-back headset audio compensation

Also Published As

Publication number Publication date
EP1119121A2 (de) 2001-07-25
ATA204099A (de) 2001-02-15
AT408298B (de) 2001-10-25
EP1119121A3 (de) 2005-12-21
JP2001237724A (ja) 2001-08-31

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AS Assignment

Owner name: AKG ACOUSTICS GMBH, AUSTRALIA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:KREMSL, ANDREAS;SCHLAGER, PETER;LANG, WERNER;AND OTHERS;REEL/FRAME:011875/0264

Effective date: 20001130

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION